GEOSTROPHIC ADJUSTMENT OF A ZERO POTENTIAL VORTICITY FLOW INITIATED BY A MASS IMBALANCE

Geostrophic adjustment of fluid in constant rotation is considered, Th e initial state is characterized by a mass imbalance, the initial velo city field is geostrophic, and zero potential vorticity Bow is imposed . The final balanced state is determined from conservation of potentia l vorticity (zero), linear momentum, and mass. The potential energy re leased during the adjustment process is partitioned into the kinetic a nd potential energies of the balanced state in the ratio 1:2, independ ent of the scale of the initial state. The development of a front (inf inite relative vorticity and a zero-order discontinuity in density) do es, however, depend on the spatial scales of the initial fields. Moreo ver, the initial position of the maximum vorticity relative to the ini tial position of the maximum density gradient significantly affects th e balanced flow. Physical interpretations of the principal features ar e provided.